The general behavior of self-healing materials is modeled including both irreversible and healing processes. A constitutive model, based on a continuum thermodynamic framework, is proposed to predict the general response of selfhealing materials. The self-healing materials' response produces a reduction in size of microcracks and voids, opposite to damage. The constitutive model, developed in the mesoscale, is based on the proposed Continuum Damage-Healing Mechanics (CDHM) cast in a consistent thermodynamic framework that automatically satisfies the thermodynamic restrictions. The degradation and healing evolution variables are obtained introducing proper dissipation potentials, which are motivated by physically based assumptions. An efficient three-step operator slip algorithm, including healing variables, is discussed in order to accurately integrate the coupled elastoplastic-damage-healing constitutive equations. Material parameters are identified by means of simple and effective analytical procedures. Results are shown in order to demonstrate the numerical modeling of healing behavior for damaged polymer-matrix composites. Healed and not healed cases are discussed in order to show the model capability and to describe the main governing characteristics concerning the evolution of healed systems.

No abstract

No abstract

In this work, a refined interelement diffuse fracture theoretical model, based on a cohesive finite element approach, is proposed for concrete and other quasibrittle materials. This model takes advantage of a novel micromechanics‐based calibration technique for reducing the artificial compliance associated with the adopted intrinsic formulation. By means of this technique, the required values for the elastic stiffness parameters to obtain nearly invisible cohesive interfaces are provided. Furthermore, the mesh‐induced toughening effect, essentially related to the artificial crack tortuosity caused by the different orientations of the interelement cohesive interfaces, is numerically investigated by performing comparisons with an additional fracture model, newly introduced for the purpose of numerical validation. These comparisons are presented to assess the reliability and the numerical accuracy of the proposed fracture approach.

A novel multiscale strategy is proposed for the damage analysis of masonry structures modeled as periodic composites. Such a computational strategy, whose aim is to reduce the typically high computational cost exhibited by fully microscopic numerical analyses, is based on a multiscale/multidomain model equipped with an adaptive capability, which allows to automatically zoom-in the zones incipiently affected by damage onset. The associated model refinement criterion requires the determination of microscopically informed first failure surfaces, which take into account both classical and bending deformation effects, by taking advantage of a couple-stress based homogenization technique. In order to assess the efficacy of the proposed multiscale modeling strategy, some numerical simulations are presented, involving a medium-sized wall test subjected to combined shear and flexure loading conditions. The related accuracy and computational performances of this methodology are investigated via suitable comparisons with a purely discrete model of masonry. Special attention is devoted to the analysis of the bending macroscopic deformation effects. Further comparisons with experimental results taken from the literature are carried out in order to validate its predictive capability in terms of peak and post-peak mechanical behavior.